The Floating Sensor Network Project

Consider the scenario known as "California Katrina" outlined in Bloomberg Businessweek this week - - Disaster in Waiting.  An earthquake or superstorm causes Gold Rush-era earthen levees to collapse.  Saltwater from San Francisco Bay floods the Sacramento-San Joaquin Delta, displacing half a million lowland Californians, poisoning the water supply for an many as 28 million more who live in L.A., San Diego, and Silicon Valley, and ruining farmland that produces 11% of the nation's agricultural value.  The eighth-largest economy in world could be sunk for months, even years.

A team at UC Berkeley has developed a potential early warning network for leaking levees and the scenerio outlined above.  They have build sensors for monitoring waterways - - a flotilla of controllable data-gathers that water resource managers could deploy to vulnerable areas, to relay information back in real time.  The theory of the sensors is straightforward.  When a levee is leaking or about to break, there are potential warning signs.  The salinity level might go haywire as seawater trickles in.  Or the water temperature can start to look odd. 

Keep in mind the Berkeley floaters are not static river monitors which are subject to being swept away and are mobility dumb.  Their network is controllablely mobile and smart - - not your basic rubber ducky.

So what is in a floating sensor?  Wired magazine this month (Flotation Device) outlined the anatomy of a self-guided sensor:

• GPS and Motorola G24 cellphone module.  Relay geotagged data in real time over a GSM network to an online server.
• Twin Motors.  Traveling about a foot per second, the unit can steer itself, say, to a place where there might be a tributary in the future, a buoyancy-control system will even let it dive below the surface.
• Depth Finder and Salinity Sensor.  Onboard instruments gather information on water conditions.  Knowing salt levels in areas where rivers and seawater collide, for example, helps assess the health of estuaries.
• Short-Range Radio.  Enables drifters to keep tabs on one another so as to avoid collisions or fan out to measure an area.
• Lithium Battery.  Powers the whole setup.  How to save power is a key.  One way to save power - - start the devices upstream of their destination and make small movements as they move downstream so they don't have to fight the current.